With Gabriel Jesus out for about 3-4 months, Im worried for Arsenal because it is a real problem for them because hes been integral to how good theyve been. Although Arsenal have not publicly disclosed Jesus's recovery timeline, but he is widely expected to spend around three months out, leaving Eddie Nketiah to shoulder the attacking burden over the rest of the winter. This position where Arsenal find themselves needs urgency because Nketiah cannot give them what Jesus has been giving them before now. They really need to dip into the market to reinforce the attack so they can maintain their position on the table.
The problem is that even if they get someone, which they can't right at this moment but during transfer window, it still leaves a good chunk of games from here until they could get someone, and it would cost a lot and a month or two later they would get Jesus back as well. All of which combined means that either getting a new player for striker or not, both is not enough for them and not a solution.
I think it would be very very important to switch up the formation and find a sustainable method within the club to make sure they do not lose games until they can figure out a way to win without Jesus, that would be the only way they could continue their run.
However, it will be more difficult for a soccer team to be able to really develop a strategy if taking players from other teams can even take longer than replacing players from their own reserve team. Even though they are not core players, because they often practice together, it will make it easier. to be able to adapt and understand the game of the team.
Apart from that, I believe that every football team always has a backup strategy that is used when their core players are injured and it can be seen that it is very rare for a team to transfer players from outside to join their team.